Surgical stapling device with lockout mechanism

ABSTRACT

A tool assembly includes a cartridge assembly and an anvil assembly pivotally secured to the cartridge assembly and movable between open and clamped positions. The cartridge assembly includes a channel member, a staple cartridge supported in the channel member, and an actuation sled positioned within the staple cartridge. The actuation sled is movable from a first position to a second position to eject staples from the staple cartridge. The tool assembly further includes a drive assembly having a clamping member movable from an initial position to an advanced position to move the actuation sled from the first position to the second position, and a lockout member secured to the channel member and moveable between a relaxed condition and a flexed condition. Movement of the actuation sled from the first position towards the second position causes the lockout member to move to the flexed condition to permit advancement of the drive assembly.

FIELD

This disclosure relates to surgical stapling devices having (fixed) single-use or replaceable cartridge assemblies. More particularly, this disclosure relates to a surgical stapling device having a lockout mechanism for preventing firing of the surgical stapling device in the absence of an actuating sled, cartridge assembly or in the presence of spent cartridge assembly.

BACKGROUND

Surgical devices for stapling tissue are well known in the art and typically include a handle assembly, a body portion extending distally from the handle assembly, and a tool assembly supported on a distal end of the body portion. The tool assembly includes first and second jaws which are movable in relation to each other between open and clamped or approximated positions. The first jaw includes an anvil assembly and the second jaw supports a staple cartridge which houses a plurality of staples.

In known surgical stapling devices, a clamping member engages the first and second jaws to move the first and second jaws from the open position to the clamped position and is movable along the first and second jaws to advance an actuation sled to sequentially eject staples from the staple cartridge. In the absence of a staple cartridge, or in the presence of a spent staple cartridge, i.e., if the actuation sled is missing, or in an advanced position, advancement of the clamping member will cause cutting of tissue without stapling tissue, resulting in complications.

A continuing need exists in the art for a surgical stapling device with a lockout mechanism for preventing undesired advancement of the drive assembly when the actuating sled or staple cartridge is not present and when the staple cartridge is spent.

SUMMARY

A surgical stapling device includes an elongate body portion and a tool assembly pivotally secured to the elongate body portion. The tool assembly includes a cartridge assembly and an anvil assembly pivotally secured to the cartridge assembly such that the tool assembly is movable between open and clamped positions. The cartridge assembly includes a channel member, a staple cartridge supported in the channel member, and an actuation sled positioned within the staple cartridge. The actuation sled is movable from a first position to a second position to eject staples from the staple cartridge. The tool assembly further includes a drive assembly having a clamping member movable from an initial position to an advanced position to move the actuation sled from the first position to the second position, and a lockout member secured to the channel member and moveable between a relaxed condition and a flexed condition. Movement of the actuation sled from the first position towards the second position causes the lockout member to move to the flexed condition to permit advancement of the drive assembly.

In certain aspects of the disclosure, the lockout member is configured to prevent advancement of the drive assembly when the actuation sled is missing, or in the second position. The actuation sled may include a ramp feature positioned to engage the lockout member as the actuation sled moves from the first position towards the second position. The lockout member may include an interlock spring secured to the channel member. The interlock spring may include a blocking portion that is located in a first position adjacent the channel member when the lockout member is in the relaxed condition and in a second position spaced from the channel member when the lockout member is in the flexed condition. The interlock spring may be welded to the channel member. The interlock spring may include an engagement portion extending distally from the blocking portion of the interlock spring.

In other aspects of the disclosure, the clamping member includes a vertical strut, an upper beam, and a lower beam. The vertical strut may include a knife. The clamping member may include a retraction ramp that is engaged by the engagement portion of the interlock spring when the drive assembly moves from the advanced position back to the initial position. Engagement of the engagement portion of the interlock spring by the retraction ramp of the clamping member may cause the interlock spring to move from the relaxed condition to the flexed condition.

A tool assembly includes a cartridge assembly and an anvil assembly pivotally secured to the cartridge assembly and movable in relation to the cartridge assembly between open and clamped positions. The cartridge assembly includes a channel member, a staple cartridge supported in the channel member, and an actuation sled positioned within the staple cartridge. The actuation sled is movable from a first position to a second position to eject staples from the staple cartridge. The tool assembly further includes a drive assembly having a clamping member movable from an initial position to an advanced position to move the actuation sled from the first position to the second position, and a lockout member secured to the channel member and moveable between a relaxed condition and a flexed condition. Movement of the actuation sled from the first position towards the second position causes the lockout member to move from the relaxed condition to the flexed condition to permit advancement of the drive assembly.

In certain aspects of the disclosure, the lockout member is configured to prevent advancement of the drive assembly when the actuation sled is missing, or in the second position. The actuation sled may include a ramp feature positioned to engage the lockout member as the actuation sled moves from the first position towards the second position. The lockout member may include an interlock spring secured to the channel member. The interlock spring may include a blocking portion that is located in a first position adjacent the channel member when the lockout member is in the relaxed condition and in a second position spaced from the channel member when the lockout member is in the flexed condition. The interlock spring may be welded to the channel member. The interlock spring may include an engagement portion extending distally from the blocking portion of the interlock spring.

In other aspects of the disclosure, the clamping member includes a vertical strut, an upper beam, and a lower beam. The vertical strut may include a knife. The clamping member may include a retraction ramp that is engaged by the engagement portion of the interlock spring when the drive assembly moves from the advanced position back to the initial position. Engagement of the engagement portion of the interlock spring by the retraction ramp of the clamping member may cause the interlock spring to move from the relaxed condition to the flexed condition.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the disclosure are described herein with reference to the drawings, wherein:

FIG. 1 is a side, perspective view of a powered surgical stapling device including a loading unit according to aspects of the disclosure having a tool assembly in an open position;

FIG. 2 is a bottom, perspective view of the loading unit shown in FIG. 1 ;

FIG. 3 is side perspective view with parts separated of the loading unit shown in FIGS. 1 and 2 ;

FIG. 4 is an enlarged view of an actuation sled indicated in the area of detail shown in FIG. 3 ;

FIG. 5 is a bottom, perspective view of the actuation sled shown in FIG. 4 ;

FIG. 6 is an enlarged view of an interlock spring indicated in the area of detail shown in FIG. 3 ;

FIG. 7 is a top, perspective view of a channel member of the loading unit shown in FIG. 2 and the interlock spring shown in FIG. 6 with parts separated;

FIG. 8 is a top, perspective view of a proximal portion of the channel member and the interlock spring shown in FIG. 7 assembled;

FIG. 9 is a side, perspective view of a clamping member indicated in the area of detail shown in FIG. 3 ;

FIG. 10 is a bottom, perspective view from the distal end of the clamping member shown in FIG. 9 ;

FIG. 11 is a bottom, perspective view from the proximal end of the clamping member shown in FIGS. 9 and 10 ;

FIG. 12 is an enlarged view of the indicated area of detail shown in FIG. 2 ;

FIG. 13 is a cross-sectional view taken along section line 13-13 shown in FIG. 1 with the tool assembly in the open position;

FIG. 14 is an enlarged view of the indicated area of detail shown in FIG. 13 ;

FIG. 15 is a bottom, perspective view of a tool assembly of the loading unit shown in FIG. 2 with the tool assembly in a clamped position and the drive assembly in a partially advanced position;

FIG. 16 is an enlarged view of the indicated area of detail shown in FIG. 15 ;

FIG. 17 is a cross-sectional view taken along section line 17-17 shown in FIG. 16 ;

FIG. 18 is the bottom, perspective view shown in FIG. 16 with the drive assembly in a further partially advanced position;

FIG. 19 is a cross-sectional view taken along section line 19-19 shown in FIG. 18 ;

FIG. 20 is the cross-sectional view shown in FIG. 13 with the actuation sled in a fully advanced position and the drive assembly in a partially retracted position;

FIG. 21 is an enlarged view of the indicated area of detail shown in FIG. 20 ;

FIG. 22 is the side, cross-sectional view shown in FIG. 17 with the drive assembly in a partially retracted position and the interlock spring in a flexed condition;

FIG. 23 is the side, cross-sectional view shown in FIG. 22 with the drive assembly in a further partially retracted position and the interlock spring in an initial or unflexed condition;

FIG. 24 is the side, cross-sectional view shown in FIG. 23 with a clamping member of the drive assembly inverted relative to the tool assembly and in the partially advanced position; and

FIG. 25 is the side, cross-sectional view shown in FIG. 24 with the drive assembly in a further partially advanced position.

DETAILED DESCRIPTION

The disclosed surgical stapling device will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the aspects of the disclosure are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the disclosure in virtually any appropriately detailed structure. In addition, directional terms such as front, rear, upper, lower, top, bottom, distal, proximal, and similar terms are used to assist in understanding the description and are not intended to limit the disclosure.

In this description, the term “proximal” is used generally to refer to that portion of the device that is closer to a clinician, while the term “distal” is used generally to refer to that portion of the device that is farther from the clinician. In addition, the term “clinician” is used generally to refer to medical personnel including doctors, nurses, and support personnel.

The disclosed surgical stapling device includes a lockout mechanism for preventing advancement of a drive assembly in the absence of an actuating sled, cartridge assembly and/or in the presence of a previously fired or defective cartridge assembly.

FIG. 1 illustrates a surgical stapling device according to exemplary aspects of the disclosure shown generally as stapling device 10. The stapling device 10 includes a powered handle assembly 20, an adapter assembly 30 releasably secured to the powered handle assembly 20, and a loading unit 100 releasably secured to the adapter assembly 30. The handle assembly 20 include a stationary grip 22 that supports actuation buttons 24 a, 24 b for controlling operation of various functions of the stapling device 10 including clamping and cutting of tissue. Although shown as individual or separable components, it is envisioned that any or all of the powered handle assembly 20, adapter assembly 30, and loading unit 100 may be integrally formed.

The stapling device 10 is illustrated as an electrically powered stapling device including an electrically powered handle assembly that may support one or more batteries (not shown). Examples of electrically powered stapling devices can be found in U.S. Pat. Nos. 9,055,943 and 9,023,014. Alternately, it is envisioned that the loading unit 100 could also be incorporated into a manual stapling device such as disclosed in U.S. Pat. No. 6,238,908 or a stapling device that is configured for use with a robotic system such as disclosed in U.S. Pat. No. 9,962,159 that does not include a handle assembly.

FIG. 2 illustrates the loading unit 100 of the stapling device 10 (FIG. 1 ) including a body portion 102 and a tool assembly 104 pivotally secured to the body portion 102. A proximal end of the body portion 102 is configured for releasable engagement with the adapter assembly 30 (FIG. 1 ).

FIG. 3 illustrates the tool assembly 104 of the loading unit 100 including a jaw assembly 106 having an anvil assembly 114 and a cartridge assembly 116. The cartridge assembly 116 includes a staple cartridge 116 a and a channel member 118 configured to receive the staple cartridge 116 a. In certain aspects of the disclosure, and as shown, the staple cartridge 116 a may be replaceable. The anvil assembly 114 and cartridge assembly 116 are pivotable relative to each other between an open position (FIG. 2 ) and an approximated or clamped position (FIG. 15 ). The anvil assembly 114 and the cartridge assembly 116 may be biased to the open position by one or more springs, e.g., leaf springs 180. The loading unit 100 is substantially as described in U.S. Pat. No. 9,016,539 (“the '539 patent”). Accordingly, the components of the loading unit 100 which are common to that which is disclosed in the '539 patent will only be described herein to the extent necessary to fully disclose the aspects of the lockout mechanism 140 and its method of operation.

A drive assembly 120 extends through and from the body portion 102 (FIG. 1 ) of the loading unit 100 into the tool assembly 104. The drive assembly 120 includes a dynamic clamping member 122 and a drive beam 124 extending proximally from the dynamic clamping member 122 into the body portion 102 of the loading unit 100. In certain aspects of the disclosure, the drive beam 124 of the drive assembly 120 is formed from a plurality of stacked sheets that are formed of a resilient or flexible material, e.g., stainless steel. A proximal end of the drive beam 124 is configured to engage a drive member (not shown) of the adapter assembly 30 (FIG. 1 ) and/or the powered handle assembly 20 (FIG. 1 ) for advancing and retracting the drive assembly 120 within the body portion 102 and the tool assembly 104.

The anvil assembly 114 of the jaw assembly 106 of the tool assembly 104 defines a longitudinal slot 151 (FIG. 13 ) and an inner clamping surface 114 a on either side of the longitudinal slot 151. In certain aspects of the disclosure, the anvil assembly 114 includes an anvil body 150 and an anvil plate 152 (FIG. 13 ) secured to the underside of the anvil body 150 to form the longitudinal slot 151. The anvil plate 152 defines a plurality of staple receiving depressions (not shown).

The channel member 118 of the cartridge assembly 116 is pivotally secured to the anvil assembly 114. The channel member 118 defines a channel 119 that receives the cartridge assembly 116. The staple cartridge 116 a of the cartridge assembly 116 of the jaw assembly 106 includes a cartridge body 156 supported in a cartridge holder 158, a plurality of staples “S”, and a staple firing assembly 160. The cartridge body 156 of the staple cartridge 116 a is secured within the channel 119 of the channel member 118 with, e.g., a snap-fit connection. Other forms of connections are contemplated and may be used in place of the snap-fit connection, or in addition thereto, to fixedly or releasably secure the staple cartridge 116 a within the channel 119 of the channel member 118. The channel member 118 further defines a longitudinal slot 161 and a clamping surface 118 a on either side of the longitudinal slot 161.

The cartridge body 156 of the staple cartridge 116 a defines a plurality of laterally spaced staple retention slots 153 which are positioned in alignment with the staple receiving depressions (not shown) in the anvil plate 152 (FIG. 13 ) of the anvil assembly 114 when the tool assembly is in the clamped position. Each retention slot 153 receives a fastener or staple “S” and a pusher 164. The staple firing assembly 160 includes an actuation sled 162 (FIG. 3 ) and a plurality of pusher members 164. The actuation sled 162 is positioned within the cartridge body 156 of the staple cartridge 116 a and is configured to pass longitudinally through the cartridge body 156 into engagement with the pushers 164 to lift the pushers within the cartridge body 156 to sequentially eject the staples “S” from the cartridge body 156.

FIGS. 4 and 5 illustrate the actuation sled 162 of the staple firing assembly 160 which includes a base portion 170, a central rib portion 172 extending upwardly from the base portion 170, and first and second paired camming rib portions 174 a, 174 b. A ramp feature 176 extends downwardly from the base portion 170 and includes an angled surface 176 a. The angle surface 176 a faces distally, i.e., away from the drive assembly 120. The ramp feature 176 may include a stop surface (not shown) for engaging a hard stop 118 b (FIG. 20 ) of the channel member 118.

FIG. 6 illustrates an interlock spring 142 of the lockout mechanism 140. The interlock spring 142 includes a pair of tang portions 144, an elongate body or spring portion 146 extending from the each of tang portions 144, and a blocking portion 148 extending between the elongate body portions 146. The tang portions 144 of the interlock spring 142 are spaced apart from one another to define a channel 145 through which the dynamic clamping member 122 (FIG. 3 ) of the drive assembly 120 (FIG. 3 ) may pass. An engagement portion 150 extends distally from the blocking portion 148. The blocking portion 148 of the interlock spring 142 defines a notch or camming feature 149.

FIGS. 7 and 8 illustrate placement of the interlock spring 142 of the lockout mechanism 140 on the channel member 118 of the cartridge assembly 116 of the loading unit 100. The channel member 118 defines a cutout 117 for receiving the interlock spring 142. The cutout 117 is formed on an underside of a proximal portion of the channel member 118. Each of the tang portions 144 is secured to the channel member 118 on either side of the longitudinal slot 161. In certain aspects of the disclosure, the tang portions 144 are welded to the channel member 118. Alternatively, the tang portions 144 may be secured to the channel member 118 in any suitable manner, including, with adhesives, mechanical fasteners, or friction fit. The interlock spring 142 is positioned on the channel member 118 such that the elongate body portions 146 of the interlock spring 142 extend distally along the channel member 118 on opposite sides of the longitudinal slot 161. When the interlock spring 142 is secured to the channel member 118, the blocking portion 148 of the interlock spring 142 extends across the longitudinal slot 161 such that the notch or camming feature 149 is centered in the blocking portion 148 of the locking spring 142 and is aligned with the longitudinal slot 161 and the engagement portion extends along the longitudinal slot 161. With only the tang portions 144 of the interlock spring 142 secured to the channel member 118, the elongate body portions 146 of the interlock spring 142 are able to flex outwardly away from the channel member 118.

FIGS. 9-11 illustrate the dynamic clamping member 122 of the drive assembly 120 which includes an upper flange portion 132, a lower flange portion 134, and a vertical strut 136 interconnecting the upper flange portion 132 and the lower flange portion 134. The upper flange portion 132 is sized and dimensioned to be slidably received within the longitudinal slot 151 (FIG. 13 ) of the anvil assembly 114 and includes a clamping surface 132 a (FIG. 10 ) that engages the inner clamping surface 114 a (FIG. 13 ) of the anvil assembly 114 to cause the pivoting of the anvil assembly 114 relative to the cartridge assembly 116 to move the tool assembly 104 from the open position to the clamped position. The lower flange portion 134 is sized and dimensioned to be slidably received along an outer surface of the channel member 118 (FIG. 15 ) and includes clamping surfaces 134 a (FIG. 9 ) facing the upper flange portion 132 of the dynamic clamping member 122. The vertical strut 136 of the dynamic clamping member 122 is received within the longitudinal slot 161 of the channel member 118 and includes a knife 136 a.

The dynamic clamping member 122 of the drive assembly 120 defines a retraction ramp 133 (FIG. 11 ) on a proximal portion of the lower flange portion 134. The retraction ramp 133 is positioned to be aligned with the engagement portion 150 (FIG. 12 ) of the interlock spring 142. The lower flange portion 134 of the dynamic clamping member 122 includes a lead-in surface 137 (FIG. 11 ) and the upper flange portion 132 of the dynamic clamping member 122 includes a lead-in surface 139 (FIG. 9 ). As will be described in further detail below, the lead-in surface 137 of the lower flange portion 134 includes an angled surface 137 a and a blocking surface 137 b, and the lead-in surface 139 of the upper flange portion 132 includes a blocking surface 139 a.

FIGS. 12-14 illustrate the loading unit 100 of the stapling device 10 (FIG. 1 ) including the staple cartridge 116 a in a pre-fired condition and the drive assembly 120 in a retracted position. In the pre-fired condition, the actuation sled 162 of the cartridge assembly 116 is in an initial position in which the ramp feature 176 of the actuation sled 162 is positioned proximal of the blocking portion 148 of the interlock spring 142, resulting in the interlock spring 142 being in an unflexed condition. When the drive assembly 120 is in the retracted position, the dynamic clamping member 122 of the drive assembly 120 is longitudinally spaced from the cartridge assembly 116 of the jaw assembly 106. Springs 180 bias the anvil assembly 114 and the cartridge assembly 116 to the open position to permit placement of tissue between tissue contacting surfaces 114 b (FIG. 13 ), 116 b of the respective anvil assembly 114 and cartridge assembly 116. In the retracted position, the dynamic clamping member 122 of the drive assembly 120 is also longitudinally spaced from the actuation sled 162.

FIGS. 15 and 16 illustrate the drive assembly 120 of the loading unit 100 in a first partially advanced position. Movement of the drive assembly 120 to the first partially advanced position, as indicated by arrow “A” in FIG. 16 , pivots the jaw assembly 106 to the clamped position, as indicated by arrow “B” in FIG. 15 . More particularly, the upper flange portion 132 of the dynamic clamping member 122 engages the clamping surface 114 a of the anvil assembly 114 and the lower flange portion 134 of the dynamic clamping member 122 engages the clamping surface 118 a of the channel member 118 to pivot the channel member 118, including the staple cartridge 116 a, to the clamped position. In the first partially advanced position, the dynamic clamping member 122 of the drive assembly 120 may be, as shown, longitudinally spaced from the actuation sled 162 to prevent any unintended advancement of the actuation sled 162 during closing of the jaw assembly 106.

FIG. 17 illustrates the drive assembly 120 of the loading unit 100 in a second partially advanced position. Movement of the drive assembly 120 to the second partially advanced position, as indicated by arrows “C”, causes the dynamic clamping member 122 to engage the actuation sled 162 to cause advancement of the actuation sled 162. Advancement of the actuation sled 162 causes the ramp feature 176 of the actuation sled 162 to engage the blocking portion 148 of the interlock spring 142 at the notch or camming feature 149.

FIGS. 18 and 19 illustrate continued advancement of the drive assembly 120 of the loading unit 100, as indicated by arrows “D”, to a third partially advanced position. The continued advancement of the drive assembly 120 to the third partially advanced position causes the continued advancement of the actuation sled 162 in relation to the interlock spring 142. As the actuation sled 142 moves distally in relation to the interlock spring 142, the ramp feature 176 of the actuation sled 162 moves beneath the blocking portion 148 to flex the elongate portions of the interlock spring 142 such that the blocking portion 148 of the interlock spring 142 lifts in the direction of arrow “E” in FIG. 19 over the ramp feature 176 and position the blocking portion 148 onto the angled surface 137 a of the lead-in surface 137 of the lower flange portion 134 of the dynamic clamping member 122. As the blocking portion 148 of the interlock spring 142 flexes away from the channel member 118, the lower flange portion 134 of the dynamic clamping member 122 can clear the blocking portion 148, thereby permitting continued advancement of the drive assembly 120.

FIGS. 20 and 21 illustrate the jaw assembly 106 of the loading unit 100 following an actuation stroke of the stapling device 10 (FIG. 1 ). The actuation sled 162 of cartridge assembly 116 is in its distal-most position following the actuation stroke of the loading unit 100 and remains in the distal-most position during retraction of the drive assembly 120. The drive assembly 120 is retracted, as indicated by arrow “F” in FIG. 20 , to a first retracted position wherein the dynamic clamping member 122 engages the interlock spring 142. More particularly, the engagement portion 150 of the interlock spring 142 engages the lower flange portion 134 at the retraction ramp 133. Engagement of the engagement portion 150 of the interlock spring 142 with the retraction ramp 133 causes the blocking portion 148 of the interlock spring 142 to flex away from the channel portion 118, as indicated by arrow “G” in FIG. 21 , such that the lower flange portion 134 of the dynamic clamping member 122 can pass over and clear the blocking portion 148, thereby permitting continued retraction of the drive assembly.

FIG. 22 illustrates the continued retraction of the drive assembly 120. More particularly, once the blocking portion 148 of the interlock spring 142 passes the retraction ramp 133 of the dynamic clamping member 122, the blocking portion 148 of the interlock spring 142 remains in engagement with an outer surface of the lower flange portion 134 of the dynamic clamping member 122 to permit the dynamic clamping member 122 to pass by the blocking portion 148 of the interlock spring 142, permitting continued retraction of the drive assembly 120 to a position in which lower beam 134 of the dynamic clamping member 122 is positioned proximally of the blocking portion 148.

FIG. 23 illustrates the drive assembly 120 in a locked position. Following a stapling procedure, the drive assembly 120 is retracted to a point in which the lower beam 134 is positioned proximally of the blocking portion 148 of the interlock spring 142. Once the lower beam 134 is positioned proximally of the blocking portion 148 of the interlock spring 142, the drive assembly 120 is prevented from being readvanced. More particularly, in the absence of the actuation sled 162 (FIG. 19 ), i.e., without the flexing of the interlock spring 142 caused by the ramp feature 176 of the actuation sled 162, the blocking portion 148 of the interlock spring 142 engages the blocking surface 137 b of the lead-in surface 137 of the lower flange portion 134 of the dynamic clamping member 122. Engagement of the blocking surface 137 b of the lower flange portion 134 of the dynamic clamping member 122 prevents continued advancement of the drive assembly 120 past the blocking portion 148 of the interlock spring 142.

FIG. 24 illustrates the drive assembly 120 within the jaw assembly 104 of the loading unit 100 in an inverted or upside-down condition. The drive assembly 120 is in the inverted condition as a result of a manufacturing error in which the dynamic clamping member 122 is positioned one hundred-eighty degrees (180°) from its correct position. In this manner, the knife 136 a is not aligned with the gap defined between the tissue contacting surfaces 114 b (FIG. 13 ), 116 b of the anvil and cartridge assemblies 114, 116, respectively. Firing of the loading unit 100 when the drive assembly 120 is in the inverted position may cause significant damage to tissue being stapled (not shown) as the knife 136 a of the dynamic clamping member 122 is not in proper alignment with the jaw assembly 106.

FIG. 25 illustrates partial advancement of the drive assembly 120, as indicated by arrow “H”, when the drive assembly 120 is in the inverted condition. The partial advancement of the drive assembly 120 causes advancement of the actuation sled 162 which cause partial flexing of the interlock spring 142, as indicated by arrow “I”. However, since the dynamic clamping member 122 is inverted, the blocking portion 148 of the interlock spring 142 engages the blocking surface 139 a of the lead-in surface 139 of the upper flange portion 132 of the dynamic clamping member 122 instead of the angled surface 137 a of the lead-in surface 137 of the lower flange portion 134 of the dynamic clamping member 122. In this manner, even in the presence of the actuation sled 162, the interlock spring 142 prevents further advancement of the drive assembly 120 when the dynamic clamping member 122 of the drive assembly is improperly installed in the stapling device 10.

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary aspects. It is envisioned that the elements and features illustrated or described in connection with the exemplary aspects may be combined with the elements and features of another without departing from the scope of the disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described aspects. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. A surgical stapling device comprising: an elongate body portion; and a tool assembly pivotally secured to the elongate body portion, the tool assembly including, a cartridge assembly including a channel member defining a channel, a staple cartridge supported within the channel of the channel member, and an actuation sled positioned within the staple cartridge, the actuation sled being movable from a first position to a second position to eject staples from the staple cartridge, the channel member defining a longitudinal slot and having an underside positioned externally of the channel; an anvil assembly pivotally secured to the cartridge assembly such that the tool assembly is movable between open and clamped positions; a drive assembly including a clamping member movable from an initial position to an advanced position to move the actuation sled from the first position to the second position; and a lockout member secured to the underside of the channel member and extending across the longitudinal slot of the channel member, the lockout member moveable between relaxed and flexed conditions, wherein movement of the actuation sled from the first position towards the second position causes the lockout member to move to the flexed condition to permit advancement of the drive assembly.
 2. The surgical stapling device of claim 1, wherein the lockout member is configured to prevent advancement of the drive assembly when the actuation sled is in the second position.
 3. The surgical stapling device of claim 1, wherein the actuation sled includes a ramp feature positioned to engage the lockout member as the actuation sled moves from the first position towards the second position.
 4. The surgical stapling device of claim 1, wherein the lockout member includes an interlock spring secured to the channel member.
 5. The surgical stapling device of claim 4, wherein the interlock spring includes a blocking portion that is located in a first position adjacent the channel member when the lockout member is in the relaxed condition and in a second position spaced from the channel member when the locking mechanism is in the flexed condition.
 6. The surgical stapling device of claim 5, wherein the interlock spring includes an engagement portion extending distally from the blocking portion of the interlock spring.
 7. The surgical stapling device of claim 6, wherein the clamping member includes a retraction ramp that is engaged by the engagement portion of the interlock spring when the drive assembly moves from the advanced position back to the initial position.
 8. The surgical stapling device of claim 7, wherein engagement of the engagement portion of the interlock spring with the retraction ramp of the clamping member causes the interlock spring to move from the relaxed condition to the flexed condition.
 9. The surgical stapling device of claim 4, wherein the interlock spring is welded to the channel member.
 10. The surgical stapling device of claim 1, wherein the clamping member includes a vertical strut, an upper beam, and a lower beam, and the vertical strut includes a knife.
 11. A tool assembly comprising: a cartridge assembly including a channel member defining a channel, a staple cartridge supported within the channel of the channel member, and an actuation sled positioned within the staple cartridge, the actuation sled being movable from a first position to a second position to eject staples from the staple cartridge, the channel member defining a longitudinal slot and having an underside positioned externally of the channel; an anvil assembly pivotally secured to the cartridge assembly and movable in relation to the cartridge assembly between open and clamped positions; a drive assembly including a clamping member movable from an initial position to an advanced position to move the actuation sled from the first position to the second position; and a lockout member secured to the underside of the channel member and extending across the longitudinal slot of the channel member, the lockout member moveable between relaxed and flexed conditions, wherein movement of the actuation sled from the first position towards the second position causes the lockout member to move from the relaxed condition to the flexed condition to permit advancement of the drive assembly.
 12. The tool assembly of claim 11, wherein the lockout member is configured to prevent advancement of the drive assembly when the actuation sled is in the second position.
 13. The tool assembly of claim 11, wherein the actuation sled includes a ramp feature positioned to engage the lockout member as the actuation sled moves from the first position towards the second position.
 14. The tool assembly of claim 11, wherein the lockout member includes an interlock spring secured to the channel member.
 15. The tool assembly of claim 14, wherein the interlock spring includes a blocking portion that is located in a first position adjacent the channel member when the lockout member is in the relaxed condition and in a second position spaced from the channel member when the lockout member is in the flexed condition.
 16. The tool assembly of claim 15, wherein the interlock spring includes an engagement portion extending distally from the blocking portion of the interlock spring.
 17. The tool assembly of claim 16, wherein the clamping member includes a retraction ramp that is engaged by the engagement portion of the interlock spring when the drive assembly moves from the advanced position back to the initial position.
 18. The tool assembly of claim 17, wherein engagement of the engagement portion of the interlock spring with the retraction ramp of the clamping member causes the interlock spring to move from the relaxed condition to the flexed condition.
 19. The tool assembly of claim 14, wherein the interlock spring is welded to the channel member.
 20. The tool assembly of claim 11, wherein the clamping member includes a vertical strut, an upper beam, and a lower beam, and the vertical strut includes a knife. 